In wireless LAN (Local Area Network) complying with the IEEE (Institute of Electrical and Electronics Engineers) 802.11a and 802.11g standards which have been actively studied in recent years, OFDM (Orthogonal Frequency Division Multiplexing) modulation is adopted as a radio transmission scheme.
The OFDM modulation is a technique for increasing frequency utilization efficiency and realizing high-speed data transmission by transmitting data using a plurality of subcarriers which are orthogonal each other.
Further, an OFDM symbol obtained by the OFDM modulation is less subject to the influence of frequency selective fading. This is because, in the OFDM symbol, data is mapped to a plurality of subcarriers having different frequencies, and therefore transmission quality of only data mapped to a part of subcarriers deteriorates due to the frequency selective fading.
In addition, as disclosed, for example, in non-patent document 1, by using the OFDM modulation and bit interleaving in combination, it is possible to correct errors in bits of subcarriers where transmission quality deteriorates due to the frequency selective fading, and further suppress the influence of the frequency selective fading. That is, by preventing consecutive bits from being mapped to the same subcarrier on the transmitting side, even if erroneous bits occur due to the frequency selective fading, the receiving side can perform error correction from preceding and following bits mapped to other subcarriers where transmission quality is good.
Non-patent document 1: “IEEE Wireless LAN Edition—A compilation based on IEEE Std. 802.11TM 1999(R2003) and its amendments” IEEE, New York, Standard IEEE 802.11, November 2003.